“Ten years ago I was just like one of those immigrants who came to this country with a single suitcase and a strong hope,” he explained. “For all of the opportunities that New York has given to me, I didn’t know how to say ‘thank you.’ But, I do now. And that is why I stand before you today.”

Mr. Krishnan’s campaign places him on a collision course with attorney and consultant Benjamin Kallos, who has said he will “absolutely” campaign for the district should Ms. Lappin leave it vacant.